1. Field of the Invention
The present invention relates to a liquid container applied to an ink jet device, and a method for manufacturing the same.
2. Description of the Related Art
Generally, in a liquid container used for a recording device which forms images or characters on a recording medium by using a recording head to apply a liquid such as ink to the recording medium, a configuration of applying predetermined negative pressure to the liquid in the liquid container has been employed to stably supply the liquid or to prevent leakage thereof.
As one example, there is a configuration which includes an absorbing member in a liquid container and uses a liquid holding force of the absorbing member to apply a negative pressure. Registered U.S. Pat. No. 5,440,333 describes a sealed type ink tank which includes upper and lower flexible members fixed to upper and lower openings of a square frame member. This ink tank contains an arched spring member. The upper and lower flexible members are expanded to the outside being pressed by the spring member to set a liquid container under negative pressure.
In the ink tank of Registered U.S. Pat. No. 5,440,333, the inner arched spring member is formed into a roughly crushed C shape by bending two arched portions. In the case of such a spring, the bent state easily becomes uneven and causes a variation in a manufacturing process. Besides, in the manufacturing process, a step of depositing a flexible film on the frame while compressing the spring may require sizable devices such as a device for compressing the spring and a device for depositing the film while fixing and holding the spring.
In the case of the ink tank having a relatively large capacity described in Registered U.S. Pat. No. 5,440,333, a negative pressure change caused by a slight spring shift or a variation has no influence. However, in the case of an ink tank having a relatively small capacity or size, there is a danger in that stability or functionality will be affected during the manufacturing process. As compared with Registered U.S. Pat. No. 5,440,333, Japanese Patent Application Laid-Open No. 2003-053988 solves the problems as follows:    (1) Adhesion planes of a flexible member and a frame portion are bonded together by forming the flexible member into a convex shape in advance; and    (2) Spring members are deformed in parallel by bonding two member components, and compressed while outer surfaces thereof are defined, in order to manufacture a device.
However, even in Japanese Patent Application Laid-Open No. 2003-053988, pressing fixtures for compressing the spring members are necessary. Moreover, when the flexible member is moved in parallel to the frame portion while maintaining planarity of a planar portion of the spring member, position accuracy, and adhesion accuracy are required, which may affect device costs and tact.